Corrosion inhibitor for metals



Faiented June 27, 1950 CORROSION INHIBITOR FOR METALS Eugene Lieber,Chicago, Ill., assignor to Nox-Rust Chemical Corporation, a corporationof Illinois No Drawing. Application December 22, 1945, Serial No.637,108

3 Claims. I

This invention relates to methods for inhibiting corrosion of metals bythe corrosive action of water vapor.

In manufacturing and commercial practices, metal objects are oftenwrapped or packaged for storing and shipping purposes and many attemptshave been made to protect the metal objects from the corrosive action ofwater vapor by carefully wrapping or packaging the metal objects inmoisture-proof wrappers or packages in order to prevent moisture fromcontacting the metal objects. In this respect elaborate schemes ofwrapping and packaging have been tried and utilized such as sealing themetal objects in as many as three or four layers of moisture-resistantwrappings. However, such schemes have not been wholly successful fordespite the best efiorts corrosion by the corrosive action of watervapor still takes place. Moisture does seek its way into the interior ofthe wrapping or package and, also, such schemes do not take into accountthe water vapor trapped in the wrapping or package when it is sealed.

The principal object of this invention is to provide new and improvedmethods of inhibiting corrosion of metal objects by the corrosive actionof water vapor wherein absolute sealing of the metal objects inmoistureproof wrappings or packages is not required and wherein moisturetrapped in the wrapping or package when it is sealed has no corrosiveeffect on the metal objects.

More specifically, an object of this invention is to associate with themetal objects to be protected a volatile compound that emits a vaporwhich deposits a corrosion-inhibiting fihn on the metal objects forpreventing Water vapor, which may be present, from corroding the metalobjects.

A further object of this invention is to treat a fibrous material, suchas paper, textile, etc., with a volatile compound that emits a vaporwhich deposits 9, corrosion inhibiting film on the metal objects to beprotected and associating the fibrous material with the metal objectsfor preventing water vapor from corrodin the metal objects. Such fibrousmaterial may be interspersed with the metal objects in a conventionalwrapping or package or it may be utilized as a part of the wrapping orpackage.

Another object of this invention is to utilize amines and amino-alcoholsas the volatile compound for emitting the vapor which deposits acorrosion inhibiting film on the metal objects to be protected.

In accordance with this invention a fibrous material, such as paper,textile, wood, etc., is treated with a volatile compound having vaporpressures such that under temperature conditions of use it will emitvapor having corrosion inhibiting characteristics. Amines andaminoalcohols having the desired vapor pressure characteristics havebeen, in accordance with this invention,'determined to be particularlysuitable as the volatile compound for emitting vapor having corrosioninhibiting characteristics.

In treating the fibrous material, it is preferably wetted by an alcoholsolution containing the amines or amino-alcohols and after drying, uponevaporation of the alcohol solvent, the fibrous material is thoroughlyand uniformly provided or impregnated with the resultant amines oraminoalcohols. The fibrous material provided or impregnated with theamines or amino-alcohols emits and continues to emit vapor havingcorrosion inhibiting characteristics as long as the fibrous materialremains coated or impregnated.

The amount of impregnation of the fibrous material, and hence thelasting qualities of the volatile compound, a course, depends upon thepercentage of amines or amino-alcohols in the original alcohol solutionand the degree of wetting of the fibrous material which in turn dependsupon the absorptive capacity of the fibrous material and the quantity ofalcohol solution applied.

From an economic viewpoint it is generally desirable to utilize theleast amount of volatile compound which will provide adequate protectionagainst corrosion for the desired length of time and, of course, theamount of volatile compound, coating or impregnating the fibrousmaterial, may be varied to suit the various applications.

For example, paper, such as conventional wrapping paper made from woodpulp stock, has been completely wetted with an alcohol solutioncontaining substantially ten per cent monoethanolamine, then dried andsuificient quantities of vapor have been emitted therefrom to protect ametal object loosel Wrapped therein for a period of weeks with nosubstantial signs of corrosion of the metal object even though thewrapping was subjected to one hundred per cent relative humidity at F.temperature over that period of time.

Other alcohol solutions of amines and aminoalcohols having substantiallythe same percentages have been similarly tried and tested withsubstantially the same results. Among the amines and amino-alcohols sotried and successfully 3 tested are ethyl diethanolamine, butylmonoethanolamine, ethyl monoethanolamine, butyl diethanolamine anddi-n-butylamino ethanol.

The ilbrous material provided or impregnated with the volatile compoundmay be utilized for corrosion inhibiting purposes in various ways.

The metal objects to be protected may beand not wasted by emission tothe surrounding atmosphere. This outer impervious covering may be aseparate covering later applied, or a compound wrapping may be utilizedhaving two laminations, one containing the volatile compound and theother being impervious to the vapors. In the latter case, the laminatedcovering, when stored preparatory to use, may be stacked or rolled sothat wasting of the vapors during the storing period may be kept to aminimum by reason of the alternate impervious layers.

Instead of the laminated construction just described a single layer 01'fibrous material may be utilized with the same general results if oneside of the layer is coated or impregnated with the volatile compoundwhile the other side is provided or impregnated with a materialimpervious .to the vapors.

Obviously, the invention is applicable to wrappings or packages in sheetform, envelope form -or carton form.

The metal objects to be protected may also be wrapped or packaged in theusual manner with -the volatile compound distributed conveniently withinthe parcel or package so that the vapors emitted therefrom will deposita corrosion inhibiting film on the metal objects. The volatile compoundmay be distributed within the parcel or package in solid state in clothbags or other porous containers or it may be sprinkled between layersofwadding or in some cases sprinkled directly into the package.

For ease of handling, uniform distribution, and proximity of thevolatile compound to the surface of the metal objects, it may bedesirable to distribute in the package fibrous material, referably instrip or sheet form, coated or impregnated with the volatile compound.In this way considerable versatility of application in packaging is madepossible.

If it be desired to protect metal inner surfaces of normally closeddevices, such as for example in engine blocks, gear casings, measuringinstruments, clocks, radio chassis and the like, the volatile compoundmay be distributed therein for emitting vapors to provide a corrosioninhibiting him on said metal inner surfaces.

Since the volatile compounds emit a, vapor which deposits a corrosioninhibiting illm on the -metal objects or the presence of water vaporwithin the wrapping or package has no appreciable corrosive action onthe metal objects or parts. It is therefore not necessary to seal themetal objects or parts from moisture as has been done in the past. It isonly necessary to prevent entry into the package or parcel ofconsiderable quantities of water and water vapor. In accordance withthis invention corrosion prevention depends on inhibition of thecorrosive action of the water vapor which gains access to the package orparcel rather than on complete exclusion of water vapor therefrom.

By ,this invention, therefore, corrosion prevention and packaging andwrapping are greatly simplified and cheapened.

Although the invention has been described with certain illustrativeembodiments, it will be apparent that changes and modifications may bereadily made without departing from the spirit and scope of thisinvention and, therefore, this invention is to be limited only by thescope of the appended claims and prior art.

I claim as my invention:

1. A product for inhibiting corrosion of metal objects comprising, amaterial provided with a composition consisting essentially of avolatile compound comprising a lower alkylol amine and having a vaporpressure to emit at temperatures of use a metal corrosion inhibitingvapor.

2. A product for inhibiting corrosion of metal objects comprising, afibrous absorbent material impregnated with a composition consistingessentially of a volatile compound comprising a lower alkvlol amine andhaving a vapor pressure to emit at temperatures of use a metal corrosioninhibiting vapor.

3. A packaging for inhibiting corrosion of metal objects comprising, alaminated sheet of material for packaging the metal objects, one of thelaminations provided with a composition consisting essentially of alower alkylol amine having a vapor pressure to emit at temperatures ofuse a metal corrosion inhibiting vapor, the other lamination being alayer which is impervious to vapors. EUGENE LJEBER.

REFERENCES CITED The following references are of record in th file ofthis patent:

UNITED STATES PATENTS Walb Oct. 19, 1948 Y .Awwii

1. A PRODUCT FOR INHIBITING CORROSION OF METAL OBJECTS COMPRISING, AMATERIAL PROVIDED WITH A COMPOSITION CONSISTING ESSENTIALLY OF AVOLATILE COMPOUND COMPRISING A LOWER ALKYLOL AMINE AND HAVING A VAPORPRESSURE TO EMIT AT TEMPERATURES OF USE A METAL CORROSION INHIBITINGVAPOR.